I was upgraded to SeaMonkey 2.53.15 today. Immediately after, Mail & Newsgroups can no longer connect to my IMAP server and access my mail. The folder and (older) messages are visible, the message frame is empty. I am not asked for my IMAP password. When I click on any message, it is not loaded. The program simply sits there with the status message "[e-mail address]: Connected to [server]..." for hours. Restart did not solve the problem.
Is this a known bug?
Many thanks, Couscous
Edit: Platform is Win 10 Pro 64, up-to-date.